All weapons and missions:
At the main menu, press L1, R2, L2, R1, R1, L2, R2, L1.Invincibility:
Press Start to pause game play, then press L1, L1, L1, R2, L1, R1, R1, L1, R2. Repeat code to disable it.Unlimited ammunition:
Press Start to pause game play, then press R1, L1, R2, R2, L2, R1, L1, R2, L2. Repeat code to disable it.
Thanks to Revolution Reader Manan.J.Gosar!